Parliament's corridors are awash with rumours of Sir Keir Starmer being replaced after a torrid few days.
Morgan McSweeney stepped down on 8 February after several Labour MPs publicly blamed him for the appointment of Lord Mandelson as ambassador to the US.
Lord Mandelson was sacked from that position in September over his links to paedophile financier Jeffrey Epstein, but new files suggested he shared confidential information with Epstein in 2009.
Less than 24 hours later, Sir Keir's communications director, Tim Allan, also quit just five months into the job.
Then Scottish Labour leader Anas Sarwar became the first senior Labour figure to call for the PM to go.
With two of his top aides gone in rapid succession and open calls for him to quit, the pressure on the prime minister to resign is mounting.
Sky News looks at how that could happen and who could be in the running to replace him.
How could Starmer be ousted?
Under Labour Party rules, a challenger, or challengers, must be nominated by at least 20% of Labour MPs (80 in the current parliament).
The challenger has to be an MP and Sir Keir, as Labour leader, would automatically be on the ballot paper.
A more realistic way Sir Keir could be ousted is if the Commons loses confidence in the PM.
Conservative leader Kemi Badenoch could table a vote of no confidence, which would require a simple majority voting with her.
However, it is rare for governments to be defeated in confidence motions, and Sir Keir could instead call a vote on a certain policy but use it as his own confidence vote.
Another tried-and-tested way to oust a prime minister is cabinet resignations, which was what happened to Boris Johnson.
The final option would be for Sir Keir to be under so much pressure he simply resigns.
Who could replace Starmer?
Angela Rayner
The former deputy prime minister remains popular with Labour members following a November poll suggesting 52% would vote for her and 33% for Sir Keir.
She remains a prominent figure in the party, despite resigning over her underpayment of stamp duty on a second home in Hove.
And her intervention in the debate that saved the government from defeat over the release of the Mandelson documents has increased her popularity.
But, the HMRC investigation into her tax affairs is ongoing and her leadership hopes could be thwarted if it is not concluded soon.
Wes Streeting
The health secretary has made no secret of his ambitions to replace Sir Keir over the past couple of months - despite allies insisting he has no intention to.
His charisma and ability to connect with the public have put him as a frontrunner.
However, Mr Streeting's close friendship with Lord Mandelson could prove detrimental to his leadership ambitions, given that is what could ultimately bring Sir Keir down.
Polling of Labour supporters for the LabourList website from 29 January to 3 February found Mr Streeting would lose against Sir Keir by 12 points.
Shabana Mahmood
The home secretary has risen quickly through the Labour ranks, having already served as justice secretary, and having been effectively endorsed by former prime minister Sir Tony Blair last year.
She has impressed the Labour leadership and is seen as a minister who gets things done - and efficiently.
However, with her tough stance on immigration, she could be seen as too right of the party - something Labour members are unlikely to be impressed by.
Ed Miliband
The former Labour leader made his cabinet comeback when Labour won in 2024 and he was made energy secretary.
He will likely be more popular than some of the others with Labour members as he is very much on the left of the party.
But, the LabourList polling found he would still lose against Sir Keir - still, only by three points.
He also has a black mark against him, having lost the 2015 general election to the Conservatives while leader.
Yvette Cooper
As foreign secretary, she is one of the most senior cabinet members - but her move from home secretary was seen as a downgrade.
She is very experienced, having served in Sir Tony and Gordon Brown's governments, and in Ed Miliband and Sir Keir's shadow cabinets.
Ms Cooper lost the 2015 Labour leadership to Jeremy Corbyn, which may count against her.
Al Carns
The newbie MP and former soldier is being tipped by a growing number of 2024 Labour MPs as a possible replacement for Sir Keir - partly through disillusionment with the other possible candidates.
He has never held a senior political role and has only been an MP for 18 months - however, both Sir Keir and Rishi Sunak were spoken about as future leaders soon after their entry to parliament.
Mr Carns' strong social media presence has also got him noticed by the public. A wild card, but one to watch.
John Healey
The steady-handed, reliable defence secretary is an experienced minister, having served under both Sir Tony and Gordon Brown.
He would be a continuity candidate and a safe pair of hands, but his closeness to Sir Keir and his moderate politics could work against him.
Andy Burnham
Greater Manchester's mayor may have had his leadership hopes already thwarted after Sir Keir blocked him from running in the Gorton and Denton by-election.
However, the Blair cabinet member could still make a comeback as an MP if another by-election cropped up - and Labour's national executive committee allowed him to stand.
(c) Sky News 2026: Who could replace Sir Keir Starmer as prime minister?
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